Scottish actor Alan Cumming (center) was in town Tuesday for one of his periodic visits to WGBH’s Calderwood Studio. As host of “Masterpiece Mystery!,” Cumming had to film intros for the series’ new season, which premieres on PBS in June. He paused to chat with Jan Egleson (left), director of the film shoot, and Rebecca Eaton (right), executive producer of “Masterpiece.”